Botany Today: Herbaria

Global map of biodiversity from GBIF occurrce data, showing continued bias in records from the Northern Hemisphere

While the articles I discussed in the last post on important questions facing plant research hardly mentioned herbaria, they are front and center in Charles Davis’s (2023) article: “The Herbarium of the Future.”  It’s an opinion piece in Trends in Ecology and Evolution, so it perhaps takes a broader view of the uses of herbaria than might be found in a systematics journal.  It is also written with a vitality, a lively pace, as if Davis is trying to fit in as much as possible about the promising future of herbaria—and plants—before a reader’s interest might flag.  But this is unlikely since he does a good job of introducing, one after another, aspects of the world of plant collections and how they can be used now and in the future in researching many questions that appeared in the lists of critical issues in the field (see last post).

Davis employs terms that connote change and growth.  His first heading is “A Revolution in Herbarium Use” where he outlines changes in herbaria and in how they are used.  One is what he terms the development of the global metaherbarium:  the growing collection of herbarium specimen data and images available on the internet, in most cases without paywalls.  The Global Biodiversity Information Facility (GBIF) is the largest of these portals, but there are many others including DiSSCo for European herbaria and iDigBio for those in the United States.  The data in these repositories overlap, and yet there really is no “metaherbarium” which harvests information from all other sources.  And there may never be, or at least it will take a long time to get there.

Davis is presenting what the plant science question group calls “horizon scanning,” peering into the future of what might be (Armstrong et al., 2023).  However, there are enormous technical difficulties in linking even collections that are using similar hardware and software.  The plus side is that as these problems have come to light so has the realization that they must be dealt with on a global level (Manzano & Julier, 2021).  The Alliance for Biodiversity Knowledge and other organizations such as the long-standing Biodiversity Information Standards (TDWG) are important forces in moving these goals forward.  The reason for urgency in effectively mobilizing data for all natural history collections is the crying need to use them for research on biodiversity and its conservation, or as Davis puts it: “Innovating Traditional Applications of Herbaria to Speed Discovery.” 

Writing of innovation and speed are rhetorical devices Davis uses to emphasize how critical the situation is.  There are still new species to be discovered, many of these already sitting in herbarium cabinets.  Could AI help to recognize some of them?  Here again, we are still in the early stages, but there have been significant advances in training machine learning systems to identify specimens.  The same is even more true of improvements in “herbariomics,” that is, extracting and sequencing DNA from herbarium specimens, even in cases where they are hundreds of years old.  Davis writes that:  “The metaherbarium soon will become the central resource for such [phylogenomic] investigations spanning populations, communities, and whole continents (p. 4).”  This is definitely on the far horizon.  If collection databases are often difficult to link together, how much more challenging will it be to extract DNA from far-flung collections?  Still, such forward thinking is essential so that possibilities feed into the groundwork now being laid for this bright future.  It includes training individuals worldwide in the skills needed to bring such work to fruition. 

The final section before the conclusion is entitled:  “Breathing New Life into Herbaria: Expanding Users and Novel Applications.”  This doesn’t require as much stretching to see the horizon because much has already happened here.  Ecologists are becoming more aware of herbaria as sources of information on life cycle traits and how they may change over time (Heberling, 2022).  Fifteen years ago phenological studies of the effect of climate change on flowering times were novel; now they have increased to the point of indicating the complexity and variety of species responses, on both small and large geographical scales.  Insect herbivory, fungal relationships, and pollinator interactions can be investigated, often by using more than one kind of natural history collection. 

Herbaria are also important in conservation work, in comparing past plant distributions with those of the present, and in studying how the genetics of populations may have changed over time.  There are really just too many ways herbaria can be used to list them all here or in Davis’s article (Funk, 2003).  However he does give a rather extensive list of uses, including devoting a full-page spread of photos from an exhibit at his home institution, Harvard University.  The Harvard Museum of Natural History opened “In Search of Thoreau’s Flowers: An Exploration of Change and Loss” in June 2022.  I’ve written about it before (see earlier post), but I want to mention it again here in the context of Davis’s article.  All 600 Thoreau herbarium specimens held at Harvard have been digitized.  These images are in the exhibit, presented through the work of several artists.  Davis is highlighting a trend that has become much more common in the 21^st century:  the use of herbarium specimens as inspiration for artists.  The great thing about this exhibit is that it remained up for almost a year, was at a popular museum, and highlighted the work of a well-known figure.  It was a wonderful way to introduce herbaria to a wider audience, while also highlighting the changes in the environment in which Thoreau collected.

References

Armstrong, E. M., Larson, E. R., Harper, H., Webb, C. R., Dohleman, F., Araya, Y., Meade, C., Feng, X., Mukoye, B., Levin, M. J., Lacombe, B., Bakirbas, A., Cardoso, A. A., Fleury, D., Gessler, A., Jaiswal, D., Onkokesung, N., Pathare, V. S., Phartyal, S. S., … Grierson, C. S. (2023). One hundred important questions facing plant science: An international perspective. New Phytologist, 238(2), 470–481. https://doi.org/10.1111/nph.18771

Davis, C. C. (2023). The herbarium of the future. Trends in Ecology & Evolution, 38(5), 412–423. https://doi.org/10.1016/j.tree.2022.11.015

Funk, V. A. (2003). 100 uses for a herbarium. American Society of Plant Taxonomists Newsletter, 17(2), 17–19.

Heberling, J. M. (2022). Herbaria as big data sources of plant traits. International Journal of Plant Sciences, 183(2), 87–118. https://doi.org/10.1086/717623

Manzano, S., & Julier, A. C. M. (2021). How FAIR are plant sciences in the twenty-first century? The pressing need for reproducibility in plant ecology and evolution. Proceedings of the Royal Society B: Biological Sciences, 288(1944), 20202597. https://doi.org/10.1098/rspb.2020.2597

Weaving Together Plant Humanities and Ethnobotany in the Future

From The Ethnobotanical Assembly, Issue 8

This series of posts is about the future of plant studies in the broadest sense.  In the first and third posts, I looked at Mason Heberling’s work on the future of herbaria, particularly in relation to plant trait research.  Between them, I wrote a post on an issue of The Ethnobotanical Assembly or T.E.A. on the plant humanities.  Several of its articles deal directly or indirectly with plant collections.  In their essay, the issue’s editors, Felix Driver and  Caroline Cornish of the University of London, include a diagram with Plant Humanities at the center of a wheel (see above) with spokes that include health, creative arts, culture, landscapes, stories, plant matter, which includes biocultural (economic botany) collections, and plant thinking, the idea that plants are sentient beings that should not be dismissed as “lower” forms of life but rather as different and equally interesting forms as animals, including humans. 

Herbaria and biocultural or economic botany collections are where many of these themes can be explored.  Author of The Plant Hunter (2021) Cassandra Quave is herbarium director and associate professor at Emory University.  She has been intrigued by the medicinal uses of plants since her college days and writes of one example of why she finds working with indigenous practitioners so important.  In another T.E.A. article called “The Herbarium as a Workshop,” Luciana Martins, a cultural historian, and Lindsay Sekulowicz, an artist, describe their collaboration on an exhibit at the Royal Botanic Gardens, Kew entitled Plantae Amazonicae.  They worked in both the Kew herbarium and its economic botany department on collections from the Amazon region made by the 19^th-century British botanist Richard Spruce.  They uncovered many interesting items used in the display, and Sekulowicz also created several artworks that commented on the collection.  These included a drawing done in ink made from pigments in the arils of seeds from the achiote shrub Bixa orellana, native to Amazonia.  Their collaboration is a beautiful example of how botanical history, indigenous culture, and art can be interwoven under the plant humanities umbrella. 

Another example of several themes tightly interwoven are found in Steeve Buckridge’s article on Jamaican lacebark from the tree Lagetta lagetto.  The species is native to the Caribbean and its inner bark has a net-like structure that made is useful as cloth.  It was employed by enslaved people who had little access to woven cloth for apparel.  It was also made into lacey decorative items that were popular among the upper classes and ultimately with tourists.  Many herbaria with biocultural collections have examples of collars, fans, and other items made from the lacebark.  But Buckridge digs deeper into the story and finds that there were multiple uses for the inner bark including twisting it into rope or weaving it to make baskets and hammocks.  The enslaved were sometimes flogged with whips made from strips of bark, so there was a dark side to its products as well.  Finally the bark had medicinal properties such as easing joint pain and healing damaged skin. 

Buckridge’s insights make a collection of objects come alive, enriched by the stories adhering to them.  His article is a good example of what can be revealed about items that are sometimes considered little more than oddities in a botanical collection.  Linking them to stories and the spokes of Cornish and Driver’s plant humanities wheel emphasize their cultural value.  This is also the theme of Mark Nesbitt’s article “Repurposing Economic Botany for the Twenty-First Century.”   Nesbitt is curator of the Economic Botany Collection at Kew and has written extensively on it and on the significance of what he terms biocultural collections in general (Nesbitt, 2014).  He reviews the history of Kew’s collection that dates back to the time of Joseph Banks and by 1910 was spread over four museum buildings, including two housing wood specimens and products.  However, as interest in the field dwindled along with Britain’s colonial empire on which it was built, the public displays became smaller and smaller.  Today, they are reduced to a few display cases in a café housed in one of the former museum buildings. 

However, the collection itself is alive and well, stored in a facility built at Kew in the 1980s, and the number of items has actually grown by a quarter under Nesbitt’s curatorship.  It is now being used in many ways, as evidenced by several articles in this T.E.A. issue.  Almost all this work involves crossing disciplinary boundaries, and Nesbitt makes the point that there are various levels to these connections.  He quotes work by the curator Henriette Pleiger who distinguishes among the concepts of multi-, inter-, and transdisciplinarity.  Multidisciplinary work is the most superficial and informal, perhaps one or more meetings among those with different expertise.  Interdisciplinary research is more interactive, long-term, and organized; it is usually more fruitful.  Nesbitt sees much of the work of the Economic Botany program at Kew as in this vein.  Finally, transdisciplinary work describes projects that seek disciplinary synthesis.  He considers this a possibility that might arise out of work Kew is doing with indigenous people in Amazonia to acquaint them with the items Richard Spruce collected in Brazil and to learn from them how these objects relate to their lived experience and history.  This seems a hopeful idea that can arise from digging deeply into biocultural collections with peoples to wh they are tied. 

References

Nesbitt, M. (2014). Use of Herbarium Specimens in Ethnobotany. In J. Salick, K. Konchar, & M. Nesbitt (Eds.), Curating Biocultural Collections: A Handbook (pp. 313–328). Richmond, UK: Royal Botanic Gardens, Kew.

Quave, C. L. (2021). Plant Hunter. New York: Penguin.

Plant Specimens in the Future

A sample of herbarium images used for training an AI model for recognizing leaf shape (Hussein et al., 2019)

In the first post in this series, I described ideas Mason Heberling (2022) presents in his paper on the role of herbaria in plant trait studies, including an outline of why specimens have been almost ignored by ecologists and evolutionary biologists in studies of genetic and environmental influences on plant characteristics.  After this survey and a convincing argument for why specimens would be valuable in this research, he discusses how herbaria could become centers for such work.  He begin this topic with a great quote from the corn systematist Edgar Anderson (1952):  “Making a good herbarium record . . . is something like trying to stable a camel in a dog kennel” (p. 47).  I imagine Anderson attempting to wrestle a corn plant, or parts thereof, onto a herbarium sheet.  But Heberling is also thinking about how plant trait studies might need not one specimen, but a number representing different parts of a plant’s life cycle or the variations found within a population.  He is realistic in considering how much more work this would mean for herbarium staff and how much more space would be needed to store all these specimens.  That’s why he argues for a reframing of the work of herbaria, which might seem like overreaching for an article on plant traits, but he makes clear that this type of research ties in nicely with the herbarium community’s present interest in the extended specimen network (ESN):  digitally tying together many types of genetic, ecological, and morphological data with specimen data (Lendemer et al., 2019). 

Heberling deals with what information should be on a herbarium sheet for trait research beyond the basics of plant name and collector as well as date and location.  Phenological data—presence of flower or fruit—is becoming more standard, but what if leaf areas have been measured or chemical analysis done?  This information is usually fed into trait databases such as Morphobank, but is not at present often linked to a specimen.  This is why Heberling calls for the participation of the functional trait researchers in building the ESN.  It would be helpful in convincing this community of the importance of vouchers to substantiate trait data.  This might not always be feasible, but at least photographic evidence could be linked.  In the other direction, it’s important for herbarium curators to be involved in developing the Open Traits Network that is attempting to standardize and integrate trait data.          

Heberling contends that rather than declaring specimens as too imperfect a form of evidence to use in trait studies, researchers should seek to change collection practices:  “We must ask how herbaria can better address the needs of new and unanticipated specimen uses.  What information do we wish that collectors a century ago had provided with their specimens?”  Then he gets more daring:  “I propose an open reevaluation of the very collection event” (p. 108).  Decisions have to be made in the digital age about what information is on the specimen itself and what is linked to it.  As one example, he cites work that he and his colleague Bonnie Isaac (2018) have done in linking online specimen data to information including photographs they input into iNaturalist at the time of a collection event. 

As to what information is actually recorded on the specimen, Heberling notes that research shows that data fields in taxonomic software are well-standardized, but the information in those fields may not be.  Anyone who compares label data to the digital record can attest to this.  Sometimes the problem may be just a random input error, but there is also the problem of fields without controlled vocabularies, or OCR difficulties, or a particular individual’s own take on what goes where.  These problems are being resolved as best practices become more widely standardized and employed.

Then there is also the issue of intensive collecting for life history or extent of variation studies.  Heberling admits that this cannot be done in all circumstances and requires budgeting for increased curatorial work and storage that might not be possible for all institutions.  But these issues definitely need to be part of conversations on the future of herbaria.  He ends by enumerating several moves that will lead to increased effectiveness and use of plant collections including archiving population-level and ontogenetic or developmental variation.  Also there needs to be more environmental context on labels.  This has become more common with habitat descriptions and associated species often listed, but available light and other abiotic conditions should be noted, and to make this information optimally useful, a standardized vocabulary should be adopted.

Also, the ENS should be built into specimen collection itself, as in the iNaturalist case; collectors should leverage the ability to create “born digital” specimens as much as possible.  The accession should also include storage of material such as silica dried leaved in fragment packets for future research requiring destructive testing.  Finally, and perhaps most importantly, collection should be planned well into the future in order to track traits at a time of climate and habitat change.  This outline for the future is a great way for Heberling to end his article that is both rich in data and in good ideas about why herbaria are important and how they can become even more significant in the future.   

References

Anderson, E. (1952). Plants, Man and Life. University of California Press.

Heberling, J. M. (2022). Herbaria as Big Data Sources of Plant Traits. International Journal of Plant Sciences, 183(2), 87–118. https://doi.org/10.1086/717623

Heberling, J. M., & Isaac, B. L. (2018). INaturalist as a tool to expand the research value of museum specimens. Applications in Plant Sciences, 6(11), e01193. https://doi.org/10.1002/aps3.1193

Hussein, B. R., Malik, O. A., Ong, W.-H., & Slik, J. W. F. (2021). Automated Extraction of Phenotypic Leaf Traits of Individual Intact Herbarium Leaves from Herbarium Specimen Images Using Deep Learning Based Semantic Segmentation. Sensors, 21(13), 4549. https://doi.org/10.3390/s21134549

Lendemer, J., Thiers, B., Monfils, A. K., Zaspel, J., Ellwood, E. R., Bentley, A., LeVan, K., Bates, J., Jennings, D., Contreras, D., Lagomarsino, L., Mabee, P., Ford, L. S., Guralnick, R., Gropp, R. E., Revelez, M., Cobb, N., Seltmann, K., & Aime, M. C. (2020). The Extended Specimen Network: A Strategy to Enhance US Biodiversity Collections, Promote Research and Education. BioScience, 70(1), 23–30. https://doi.org/10.1093/biosci/biz140

Swiss Treasure Rooms

Facing pages from Felix Platter’s Herbarium. Bern City Library.

This post in the series (1,2) on the whereabouts of early modern herbaria begins with two notable collections in Switzerland, Felix Platter’s (1536-1614) at the Bern City Library and Caspar Bauhin’s (1560-1624) at the University of Basel’s herbarium.  Both are significant and both were the subject of an article by Davina Benkert (2016), where she does a wonderful job of describing each and comparing them.  As with many collections this old, portions are missing.  Platter eventually bound his specimens and had 18 volumes of which nine survive.  In many cases, he pasted a plant on the right hand page and one or more illustrations on the left.  Among these are prints as well as watercolors, including 77 by Hans Weiditz, the originals of the plates used in Otto Brunfel’s 1530 Herbarum vivae eicones.  Paper being valuable, Weiditz had painted on both sides of each sheet.  Wanting to get the most out of them, Platter cut them out so he could use both plants, sometimes painting in parts that were missing.  He also at times “fiddled” with specimens, such as pasting stamens to the outside of tulip flowers to make them visible.  These practices horrify present-day art historians and botanists, but this was early modern botany and techniques had yet to be codified. 

Bauhin was Platter’s student at the University of Basel and they collected together.  Eventually Bauhin joined the faculty and worked on his plant compendium, Pinax theatri botanici published there in 1623.  They used the specimens differently, so they treated them differently.  Platter used his in teaching and as reference.  Though he had early on kept his specimens loose, he eventually preferred bound volumes because they allowed him to show his collection to visitors, something he relished, without damaging the plants.  He used Bauhin’s classification system.  Even though it hadn’t been published yet, he was obviously privy to the manuscript.   

On the other hand, Bauhin was trying to build a comprehensive collection to use in creating a planned work on taxonomy.  He kept his specimens loose, slipped between folded sheets of paper with identification slips.  This enabled him to reorganize them as his ideas about relationships among them changed, but it also meant fragments and labels could easily slip out.  It also made it easier to remove specimens.  Bauhin’s collection continued to be used for teaching and reference after his death.  His descendants allowed botanists to select specimens, which explains why two-thirds of the originals are gone (Benkert, 2016).  In 1774, what remained was purchased by Werner von Lachenel, a University of Basel botanist who integrated the sheets into his own herbarium.  When the University acquired his herbarium, they then sorted out Bauhin’s sheets, but 400 were in such poor condition they were discarded.  Here at least we have some idea of why the collection is so greatly reduced.  In many cases, the dwindling of a collection isn’t as well documented.  I should add that sometimes items are later found as when 300 of Ulisse Aldrovandi’s specimens (see last post) were discovered in a later Italian collection (Mossetti, 1990).  Again, this might seem horrifying, but it is really a form of borrowing, a common practice; it’s just that in the Bauhin and Aldrovandi cases it was done posthumously. 

Alette Fleischer (2017) has written an article with a great title Leaves on the Loose and subtitled “The Changing Nature of Archiving Plants and Botanical Knowledge” and that deals with these issues.  She notes that when herbaria were unbound all ties could be lost to the history of a sheet and who made it.  She sees the digitization of old collections as a boon to “recombining” specimens, setting them next to each other for comparison.  James Petiver, an avid British collector, amassed over 100 herbaria, which eventually become part of Hans Sloane’s herbarium, now at the Natural History Museum, London.  Fleisher writes that “According to his beliefs on order, Petiver compiled, or more precisely recompiled nearly every herbarium that came into his possession.  .  .  .  He not only took sheets from older herbaria, but also cut out bits of paper and plants and glued these together with other specimens, thereby losing labels, names, and information” (pp. 125-126).

Reading statements like this explains a lot about why the early history of herbaria is fragmentary.  It also makes what is available that much more wonderful.  Particularly wonderful is the website that has been created around Platter’s herbarium, with the pages organized by volume and by species names.  In addition there are webpages with information on Platter and the collection’s history.  It’s thrilling to be able to closely study the pages, especially those with Weiditz images.  The University of Basel herbarium website states the Bauhin herbarium has been imaged, but I could not find a link to it, so I am not sure if it is available online.  In time it probably will be, another wonderful digital treasure.  In the meantime, the Platter volumes would keep anyone with an interest in early modern botany busy for a long time. 

References

Benkert, D. (2016). The ‘Hortus Siccus’ as a focal point: Knowledge, environment, and image in Felix Platter’s and Caspar Bauhin’s herbaria. In S. Burghartz, L. Burkart, & C. Göttler (Eds.), Sites of Mediation (pp. 211–239). Leiden: Brill. https://doi.org/10.1163/9789004325760_010.

Fleischer, A. (2017). Leaves on the loose: The changing nature of archiving plants and botanical knowledge. Journal of Early Modern Studies, 6(1), 117–135. https://doi.org/10.5840/jems2017616.

Mossetti, U. (1990). Catalogue of Ulisse Aldrovandi’s herbarium: The specimens found in the herbaria of Giuseppe Monti and Ferdinando Bassi. Webbia, 44(1), 151–164. https://doi.org/10.1080/00837792.1990.10670471.

Open the Treasure Rooms

Tomato specimen from the En Tibi herbarium, Naturalis Biodiversity Center, Leiden

This post’s title comes from Tinde van Andel’s inaugural lecture as Clusius Chair of History of Botany and Gardens at Leiden University in the Netherlands:  Open the Treasure Room and Decolonize the Museum.  Working with a team of researchers, the room van Andel is exploring is at the Naturalis Biodiversity Center and is indeed a particularly rich collection.  It has a number of 16^th-century herbaria, including the En Tibi dated to about 1554 and attributed by van Andel and her team to Francesco Petrollini, a student of Luca Ghini who was at least an early proponent if not the originator of preserving pressed specimens (Stefanaki et al., 2019).  Petrollini is also now thought to have created a herbarium in Rome’s Angelica Library that had been attributed to another Ghini student, Gherardo Cibo.  It was begun in 1532, making it the earliest extant collection.

Also in Leiden are herbaria created by Leonhard Rauwolf who collected in France as well as in the Middle East (see earlier post).  Van Andel’s commented in her lecture that when she showed specimens of sorghum, eggplant, and pistachio that Rauwolf had found in agricultural plots in Syria, it was the first time in over 400 years that someone from the Middle East had set on eyes on them.  These plants document what was being grown at the time and may yield DNA revealing more about the history of these crops (Ghorbani et al., 2018).  That they are physical evidence for plants of the past is one reason the collections are treasures.

As another example of what these riches have revealed, van Andel, working with molecular biologists as well as historians, has taken a look at the early history of the tomato in Europe.  They have recently published on this work, presenting specimens as well as illustrations, putting together a possible timeline of how the plant spread through Europe from Spain to Italy and then to northern Europe (Andel et al., 2022).  The fact that there was quite a bit of evidence suggests interest in this strange fruit.  The specimen in En Tibi even has half a tomato attached.  A small portion of a leaf was removed and DNA extracted from it; research suggests that it was a domesticated plant.  Petrollini probably obtained seeds from Ghini, who may have gotten them from a former student Luigi Anguillara, director of the botanical garden in Padua near Venice, which was a busy port where many exotic species arrived.  So this one page of En Tibi reveals much not only about the plant’s biology but also about its history in Europe and about how a tightly knit botanical network enabled rapid transmission not only of information but of seeds and other botanical material. 

For a long time, early herbaria were ignored, as van Andel’s comment about Rauwolf’s collection indicates.  Any pre-Linnaean herbarium that had not been studied by Carl Linnaeus and therefore not used by him in naming species was considered irrelevant to modern botany, which dates from the publication of Linnaeus’s Species Plantarum of 1753.  The collections were deemed worth keeping, but not worth serious study.  This has changed recently for a number of reasons, including the renewed interest in natural history collections in general as sources of information about biodiversity.  There is also interest in botany’s social history as the second half of van Andel’s title suggests:  decolonize the museum.

The Netherlands was an important naval power with an eye on botanical riches such as nutmeg and cinnamon from the East, but any plants of interest were welcomed in the homeland by eager gardeners looking for novelty.   One collection in Naturalis was created around 1587 by an unnamed Dutch collector working in what is now Suriname.  It preserves plants native to the area and also African food plants—okra and sesame (Andel et al., 2012).  This indicates that the plantation culture, with the presence of African enslaved persons, had brought with it new species, one of many examples of the early movement of plants with links to the slave trade.  It shows how herbaria can contribute crucial evidence on cultural and political history and can help clarify portions of history that have long remained hidden, including the early pervasiveness of enslaved labor in the Americas.

I have focused on the Leiden treasure room in this post, but in the others in this series I’ll mention herbaria kept in collections throughout Europe.  Some, like part of Felix Platter’s collection in Basel, had been there for hundreds of years but had only been rediscovered in the 1930s.  Others, like Ulisse Aldrovandi’s in Bologna were cared for over the centuries, but still, it wasn’t investigated until recently.  One reason for the increased attention is that there have been efforts to digitized important cultural collections of all kinds, making the 15 volumes of Aldrovandi’s herbarium available to a wider audience and also making it much easier to compare specimens of the same species from different collections, as done in the paper on the history of the tomato. 

To me this is the exciting thing about what could be considered the renaissance of Renaissance herbaria:  allowing careful study without necessarily disturbing the very fragile originals.  I would love to experience the physical heft of En Tibi or see the pages that Rauwolf saw as he, or an assistant, reinforced/decorated them with patterned paper.  However, the very newest of technologies have made these oldest of specimens available to all, even in the age of covid.  The important thing now is to mine these works thoroughly to learn more about plants and botanists in the early modern era. 

References

Andel, T. van. (2017). Open the treasure room and decolonize the museum [Inaugural lecture]. Leiden University. https://openaccess.leidenuniv.nl/handle/1887/51665.

Andel, T. van, Veldman, S., Maas, P., Thijsse, G., & Eurlings, M. (2012). The forgotten Hermann Herbarium: A 17th century collection of useful plants from Suriname. Taxon, 61(6), 1296–1304. https://www.jstor.org/stable/24389114.

Andel, T. van, Vos, R. A., Michels, E., & Stefanaki, A. (2022). Sixteenth-century tomatoes in Europe: Who saw them, what they looked like, and where they came from. PeerJ, 10, e12790. https://doi.org/10.7717/peerj.12790.

Ghorbani, A., Wieringa, J. J., de Boer, H. J., Porck, H., Kardinaal, A., & van Andel, T. (2018). Botanical and floristic composition of the Historical Herbarium of Leonhard Rauwolf collected in the Near East (1573-1575). Taxon, 67(3), 565–580. https://doi.org/10.12705/673.7.

Stefanaki, A., Porck, H., Grimaldi, I. M., Thurn, N., Pugliano, V., Kardinaal, A., Salemink, J., Thijsse, G., Chavannes-Mazel, C., Kwakkel, E., & Andel, T. van. (2019). Breaking the silence of the 500-year-old smiling garden of everlasting flowers: The En Tibi book herbarium. PLOS ONE, 14(6), e0217779. https://doi.org/10.1371/journal.pone.0217779.

The Plant Humanities Lab

Figure adapted from the Biodiversity Collections Network’s 2019 report: Extending U.S. Biodiversity Collections to Promote Research and Education

I’m interested in herbaria writ large, that is, how they relate not only to areas of biology beyond botany, but to the arts and humanities.  That’s why I’ve delved a bit into the field of digital humanities and how it might enrich the herbarium world.  From what I can gather the term digital humanities covers a lot of territory, but all related in some way to harnessing digital technology.  This can range from textual analyses such as tracing the frequency of use of a term in Emily Dickinson’s poetry to creating an online archive that brings together all her poems.  There’s also a great deal of work on developing new tools for visualizing social networks, linking different types of information, and creating new forms of communication.

In many cases, the humanities are doing much the same thing that the natural history community is doing:  using digital tools to not only make resources available online but to provide tools to use these resources in powerful and creative ways.  The problem is that the two are working in separate spheres and approaching similar issues in different ways, suggesting that the two cultures of C.P. Snow (1959) survive into the 21^st century.  Snow (1905-1980) was a physical chemist and novelist; functioning successfully in the two spheres allowed him to appreciate what divided them.  Since he wrote, a great deal of work termed “interdisciplinary” has attempted to bridge the divide that Snow saw as dangerous, with each side unable to appreciate the other’s perspective.  Yet the problem remains.

My pet example is one that I’ve brought up here before.  What is coming to be called the Digital Extended Specimen is the vision that eventually a natural history specimen can be linked to many other types of information including species’ genome sequences, ecological data, field notes, field images, phylogenies, etc. (see figure above).   The focus in these conversations is on various scientific databases linking to each other.  This is a massive job and one that is just beginning.  But what I would like to see, even at this early stage—particularly at this early stage—is to make the job more massive by building history and art collections into the infrastructure.  Now is the time to do it, when frameworks on both sides are still being developed and haven’t yet become so complex that adaptation becomes almost impossible.  The FAIR principles for scientific data management could also apply in the other areas, making digital objects:  Findable, Accessible, Interoperable, and Reusable. 

While I’ve painted a rather bleak picture of two realms unable to talk to each other, there are some wonderful projects that do link science and the humanities in interesting ways.  In the botanical world, perhaps the most notable at the moment is the Plant Humanities Lab, a joint project of the Dumbarton Oaks Research Library and JSTOR Labs.  This grew out of what could only be termed a summit at the library that included botanists, historians, librarians, and technology experts.  They outlined a series of different approaches to linking botanical, historical, and cultural resources (see video).  This was just a set of ideas, and over the next few years the library and JSTOR developed a plan and received funding from the Andrew W. Mellon Foundation to create the Plant Humanities Lab. 

The lab’s first manifestation was a set of narratives on such plants as boxwoods, watermelons, agaves, and bananas.  Each gives a well-written introduction to the species and outline not only its biology but its social history as well.  The narratives, richly illustrated, often with art from the Dumbarton Oaks collection, have hyperlinks to more information on everything from species descriptions to food, gardening, and colonial exploitation of crops and medicinal plants.  They do indeed connect history, art, and science, revealing how these are inseparable from each other.  These are wonderful stories for those interested in delving deeper into particular aspects of a plant.  One thing that becomes clear is that the history of plant use by humans is a long and winding road, sometimes stretching back millennia, with many problems along the way including the difficulties of breeding plants wrested from their native soils and brought to very different climates.  Then there was the use of indigenous knowledge about plants without in anyway acknowledging it and with no benefits to those who provided it.  In addition, there are the intriguing characteristics of so many of these species.  The subjects seem to be chosen carefully to provide many paths to different kinds of information in order to attract a variety of audiences who can explore them in their own ways. 

It’s obvious when using this site that it has a sophisticated framework.  Created by JSTOR labs over several years, the wonderful thing about it is that this digital tool is open access and now available to users as Juncture in the Beta version.  It does involve some knowledge of coding and accessing needed tools from GitHub, so this will pretty much eliminate people like me from using it.  However, we can still benefit from the sites created by those who do use it, and from the continuing development of new and more sophisticated plant narratives.  One problem with Juncture is that is allows linking to so many different kinds of information that there are endless rabbit holes to fall into, but each is just another wonderful aspect of the plant world.  Also it can be used to create narratives on any subject.  JSTOR is developing it as a tool of the future for education and research.

Reference

Snow, C. P. (1959). The Two Cultures and the Scientific Revolution. New York: Cambridge University Press.

Ethnobotany

Palm basket from Botswana in the Kew Economic Botany Collection

As the twentieth century progressed and economic botany went into decline (see last post), ethnobotany developed and incorporated some of the former’s collections and concepts.  Merlin Sheldrake (2020) defines ethnobotany as the study of the relationships among plants and people, in other words, learning about plants through people’s attitudes towards and uses of them.  Because ethnobotany grew out of studies of plants and indigenous peoples, its emphasis has been on plant use among these populations and is often related to anthropological studies.  Richard Schultes was a botanist instrumental in making the transition from economic botany to ethnobotany.  He studied economic botany with Harvard’s Oakes Ames in the 1930s and wrote his undergraduate thesis on the use of peyote cactus as a hallucinogen among the Kiowa people of Oklahoma.  Schultes went on to pursue both taxonomy and ethnobotany.  Like many botanists who are involved in more than one facet of the science, he collected specimens because he needed to be able to identify the species he found in the field and to study their relationships not only to human use but to each other (Ponman & Bussmann, 2012).

Oakes Ames had early warned of the need to learn as much as possible about plants and their uses from indigenous peoples because they and their life styles were so vulnerable.  Schultes heeded his mentor’s warning and recorded much about the peoples he studied within tropical South America, especially their use of hallucinogenic plants in religious rituals.  He wrote a great deal and also educated the next generation of ethnobotanists.  Ethnobiology is still evolving as a discipline, and in the 21^st century it is becoming more central to efforts to promote conservation, equitable distribution of resources, and sustainability. 

In the second half of the 20^th century, pharmaceutical companies funded many expeditions with the goal of finding plant-derived active substances.  About a quarter of prescription drugs are produced from plant materials or based on chemicals first found in plants, so this strategy makes sense.  There are two approaches to plant hunting for pharmaceuticals.  One is to collect enough material from an array of plants in a region to test each for chemicals such as alkaloids, a molecular class that includes many drugs.  Interesting substances have been discovered this way, but it is rather hit or miss (Blumberg, 1998).   

The other approach to drug discovery is to partner with indigenous peoples, particularly with healers who use local plants to treat a variety of maladies.  This has been done since the arrival of the first European explorers, but now the work is much more respectful of local knowledge.  Experts in ethnobotany live with indigenous peoples and make it a practice to learn the languages of the groups they work with, understanding the culture as well as the plants and studying healing practices and other uses of plant materials (Balick & Cox, 1996).  Ethnobotany provides a more holistic approach to drug discovery, studying the culture as a whole.  In some locales for example, palms are pivotal plants as sources not only of medicines, but of food, building materials, containers, and even cloth (See image above). 

Abena Osseo-Asare (2014) investigated efforts to develop drugs from African medicinal plants and discovered that researchers often consulted the herbaria of colonizers to find likely locations for plants that might yield active ingredients.  So even though African nations had achieved independence, colonial influence remained.  However, she also found it difficult to create a simple narrative of exploitation.  Drug development is a complex process, and most areas of Africa do not yet have the infrastructure for research and development independent of multinational corporations.  Osseo-Asare’s research also revealed that many likely medicines were hardly new to science, their existence had long been known and could not be attributed to a particular indigenous group or area.  This meant that compensation would be difficult to negotiate.  Robert Voeks (2018) has also questioned the “jungle medicine narrative,” writing from his perspective as a botanist who spent much time in the tropics studying medicinal plants.  He has great respect for indigenous knowledge, but is less positive about how likely it is that useful drugs can arise from these resources because the diseases of the developed and developing worlds are so different from each other.

Ethnobotanical research, for medical or other aims, requires herbarium vouchers to document the plants discussed in reports and other publications.  Having a preserved specimen, a voucher, allows future investigators to verify the species tested.  Also, since herbal medicines are essentially formulations of plant material, it is considered good practice in their manufacture to voucher each batch of plants used, though the term “batch” can mean many different things.  Ideally, it would be the plants collected in a certain place at one time by a single collector or group working together.  This is not always feasible, but it is definitely a useful goal (Eisenman et al., 2012). 

References

Balick, M. J., & Cox, P. A. (1996). Plants, People, and Culture: The Science of Ethnobotany. New York: Scientific American.

Blumberg, B. S. (1998). Case Study of Plant-Derived Drug Research: Phyllanthus and Hepatitis B Virus. In T. R. Tomlinson & A. Olayiwola (Eds.), Medicinal Plants: Their Role in Health and Biodiversity. (pp. 3–10). Philadelphia: University of Pennsylvania Press.

Eisenman, S., Tucker, A., & Struwe, L. (2012). Voucher specimens are essential for documenting source material used in medicinal plant investigations. Journal of Medicinally Active Plants, 1(1), 30–43.

Osseo-Asare, A. D. (2014). Bitter Roots: The Search for Healing Plants in Africa. Chicago: University of Chicago Press.

Ponman, B. E., & Bussmann, R. W. (Eds.). (2012). Medicinal Plants and the Legacy of Richard E. Schultes. St. Louis: Missouri Botanical Garden.

Sheldrake, M. (2020). The ‘enigma’ of Richard Schultes, Amazonian hallucinogenic plants, and the limits of ethnobotany. Social Studies of Science, 50(3), 345–376. https://doi.org/10.1177/0306312720920362

Voeks, R. A. (2018). The Ethnobotany of Eden: Rethinking the Jungle Medicine Narrative. Chicago: University of Chicago Press.

Getting the Most Out of Herbaria: In So Many Ways

Images from Tweet sent by the Georgia Southern University Herbarium

So far in this series of posts on the uses of herbarium specimens in research (1,2,3), I’ve stuck to those that are most commonly discussed:  taxonomic and floristic work, environmental change studies, and phylogenetics.  But there are many other uses, with the variety increasing because digitization makes specimen information more easily available to a broader audience.  There have been studies on the presence of plant pathogens in specimens, including fungal infections (Kido and Hood, 2019).  Anther smut was found detected on specimens through visual inspection under a microscope (Antonovics et al., 2003).  Recently, sensitive DNA sequencing techniques have made it possible to detect bacterial infections by differentiating between pathogen and host DNA.  There is even Defense Department interest in such research.  The Center for the Study of Weapons of Mass Destruction in Washington DC issued a report where they outline why natural history collections can be sources of information in the work of protecting against biological warfare.

Different groups of researchers look at herbarium specimens very differently.  Those investigating fungi might focus on the roots, such as in a study about the successful extraction of arbuscular mycorrhizal fungal DNA from vascular plant roots.  Other botanists have developed techniques for systematically evaluating the amount of herbivore damage to leaves by using a grid system (Meineke & Davies, 2019).  While it’s common to find dead insects on a specimen, snails hiding out are more of a surprise.  Researchers examining lichens and bryophytes from the Galapagos Islands found that 10% of 400 specimens had at least one of eight different micro-mollusk species adhering to them.  There was even a new species discovered.  It is not unusual for new plant species to be found among herbarium specimens (Bebber, 2010), but snails are another thing.

Specimens can also be useful before trips to collect more specimens; Kew Botanic Gardens has a handbook with specimen images as a guide for collectors.  Searching databases for where a particularly narrowly endemic species was found in the past increases a botanist’s chances of finding it again.  One approach is searching for associated species in locality information.  Botanists are being encouraged to list such data to make specimens more valuable in ecological studies.  Another way to enhance specimens is to link them to other types of data such as iNaturalist observations from the same locale.  Heberling and Isaac (2019) describe how they are doing this at the Carnegie Museum of Natural History’s herbarium in Pittsburgh.  The iNaturalist data can include photos taken on the site by citizen scientists.  These visual records may document traits such as flower color and form that are difficult to preserve in dried specimens.   There may also be information about the surrounding habitat.  Having these items linked to specimens is a step toward the development of what is termed the Extended Specimen Network, with the specimen is at the center of linked resources providing information on the genetics, ecology, and morphology of the species (see earlier post).

Besides scientific uses, herbaria can also have what could be termed sociological uses.  There are several ways in which digitization of natural history collections could lead to more diversity among researchers.  Online access means that those interested in taxonomy who are living in developing nations can more easily access not only specimen data but related research through such portals as GBIF.  This also makes it easier for them to find research partners in developed nations.  A very different approach to expanding diversity has been employed by several institutions in the United States:  enlisting those in juvenile detention centers and those recently released from such facilities in digitizing specimens.  These projects not only provide employment, but also broaden the participants’ experience of science and of working with databases.  It is a nice example of thinking more creatively about expanding the population of those interested in nature and opening up herbaria in novel ways.  The iDigBio project held a webinar on this topic to make the natural history collection community aware of this approach, document the progress that has already been made, and encourage other ways to think outside the box in drawing people to natural history.

I haven’t mentioned using herbarium collections in outreach programs because I covered this in a recent post.  However, I have recently come across a few examples that seem too good to ignore.  The first is a “Hookathon: Hacking the Herbarium” at the Royal Botanic Gardens, Kew.  This was an all-day citizen science event to digitize items in Kew’s massive collection of material related to Joseph Dalton Hooker, who led the garden for many years during the second half of the 19^th century.  This was also a means to advertise the collection’s existence and its variety, including specimens, manuscripts, letters, and drawings.  At the University of Manchester in Britain, the herbarium opened its doors to students during the exam period for “well-being” events so they could unwind by drawing specimens and incidentally find out what a herbarium is about.   I would like to end with a political, yes a political, example of outreach.  A Tweet from the Georgia Southern University Herbarium reminded residents about voting and put in a plug for the state symbol, the peach, with a beautiful fertile specimen.  This is outreach at its most creative.

References

Antonovics, J., Hood, M. E., Thrall, P. H., Abrams, J. Y., & Duthie, G. M. (2003). Herbarium studies on the distribution of anther-smut fungus (Microbotryum violaceum) and Silene species (Caryophyllaceae) in the Eastern United States. American Journal of Botany, 90(10), 1522–1531.

Bebber, D. P., Carine, M. A., Wood, J. R. I., Wortley, A. H., Harris, D. J., Prance, G. T., Davidse, G., Page, J., Pennington, T. D., Robson, N. K. B., & Scotland, R. W. (2010). Herbaria are a major frontier for species discovery. Proceedings of the National Academy of Sciences, 107(51), 22169–22171.

Heberling, J. M., & Isaac, B. L. (2018). iNaturalist as a tool to expand the research value of museum specimens. Applications in Plant Sciences, 6(11).

Kido, A., & Hood, M. E. (2020). Mining new sources of natural history observations for disease interactions. American Journal of Botany, 107(1), 3–11.

Meineke, E. K., & Davies, T. J. (2019). Museum specimens provide novel insights into changing plant–herbivore interactions. Phil. Trans. R. Soc. B, 374(1763), 1-14.

Getting the Most Out of Herbaria: The Environment

Website for the California Phenology Project

A major argument used for preserving and digitizing natural history collections is that they contain critical information useful for researchers attempting to understand climate change.  This idea is now so much a part of the herbarium communities’ thinking that I hesitate to mention it, but there are some interesting examples worth noting on how botanists are mining collections.  Phenological research on specimens have been going on for years and its success in documenting changes in flowering, fruiting, and other points in plant life cycles have bred more such work.  This has gotten to the point where digitization efforts have become more focused on carefully documenting the phenological status of plants in a rigorous and systematic way, so this information can be mined from databases.  The NSF is sponsoring a project of the California Herbarium Consortium to do just this, including training citizen scientists to identify phenological status and record it in the online specimen records (Yost et al., 2020).

However, there isn’t a clear cause and effect relationship between increasing temperature and phenology.  Some species seem more affected than others, and some show little effect, with many factors involved in these differences.  Also, phenological changes can lead to more than just a habitat too warm for a particular species.  For certain orchid species, flowering times have not changed, but the emergence their pollinators have been pushed earlier.  This means that the pollinators will not find the resources they need from these orchids, and when the flowers do bloom, the insects they rely on may no longer be around or may have moved on to other species.  It’s a complicated dynamic, which is why a variety of species in many different habitats need to be investigated.

One cause of climate change—carbon dioxide (CO₂) increases in the atmosphere—can have effects on plant physiology and morphology.  Not surprisingly these include an impact on the apparatus for the process that uses the gas, namely photosynthesis.  Researchers in New Zealand measured stomatal density on leaves in specimens from their national herbarium.  Since stomata are the leaf structures that allow in CO₂, their number indicates how much of the gas a leaf can absorb at one time.  Some material in the study dated back to Captain James Cook’s first voyage to New Zealand in 1769-1790.  Since the specimens were so old and fragile, the botanists employed an indirect technique to examine the leaves.  After painting the leaves with gel that was allowed to harden, they gently removed the film, which had an impression of the stomata from the leaf surface.  Karaka tree leaves (Corynocarpus laevigatus) gave particularly good prints.  Fortunately, specimens of this species had been collected at several sites.  The researchers also counted stomata on Karaka leaves collected in the late 19^th century, as well as modern specimens and fresh material.  There was little difference in stomata density between the 18^th and 19^th century, but the modern-day leaves had about 50% fewer pores, suggesting that increased CO₂ concentrations in the air meant that the plant could absorb the same amount of gas while expending less energy creating these structures.  I went into this example in some detail to show the thinking and work involved in any one study to provide a single piece of information about the climate change puzzle.

While fungi are not technically plants, historically they have been treated as such, remain in many herbarium collections, and are studied by those who call themselves botanists.  Researchers at the University of Arizona have created a collection of 7,000 specimens of endophytic and endolichenic fungi, that is, those that live inside the cells of healthy plants and lichens respectively.  This team emphasizes that they are dealing with healthy organisms, since the fungi are beneficial rather than harmful to their hosts.  These fungi are receiving a great deal of attention because of their importance in moving nutrients between plants and the environment.  What makes this particular collection significant is that it is not historical.  It was created in the digital age, with all the information entered directly into a database with extensive metadata on location and host, as well as genetic sequencing data, namely DNA barcodes.  The latter provide a way to identify many fungi that are otherwise difficult to distinguish from one another.  The organisms were collected from a variety of plant and lichen hosts at 50 locations throughout Arizona, representing a range of habitats.   Because the resulting database is so sophisticated, researchers were able to analyze the data and “highlight the relevance of biogeography, climate, hosts, and geographic separation in endophyte community composition” (Huang et al., 2018, p. 47).

Another Arizona study was done by a student at Arizona State University who collected weedy plants from alleyways in Tempe, Arizona.  He used the SEINet database of southwestern plant specimens to attempt tracking the first occurrence of these weeds in the area.  He collected specimens from 83 species, but was only able to trace a portion of these back to early introduction.  However, the study serves as a baseline for future work on urban weeds, a topic gaining more attention.  A small but useful study done in Mexico showed that the measure of weediness among a group of related species was about the same when based on field observations versus herbarium specimens.  They employed a recognized scale of synanthropy, that is, the “degree to which a species associates with human-caused disturbance” (Hanan-A et al., 2016, p. 1).  They found that the index generated comparable weediness ratios from field observations and herbarium specimens, indicating that specimens could be used to measure weediness.

References

Hanan-A., A. M., Vibrans, H., Cacho, N. I., Villaseñor, J. L., Ortiz, E., & Gómez-G., V. A. (2016). Use of herbarium data to evaluate weediness in five congeners. Annals of Botany Plants, 8.

Huang, Y.-L., Bowman, E. A., Massimo, N. C., Garber, N. P., U’Ren, J. M., Sandberg, D. C., & Arnold, A. E. (2018). Using collections data to infer biogeographic, environmental, and host structure in communities of endophytic fungi. Mycologia, 110(1), 47–62.

Yost, J. M.et al. (2020). The California Phenological Collections Network: Using digital images to investigate phenological change in a biodiversity hotspot. Madroño, 66(4), 130–141.

Getting the Most Out of Herbaria: Systematics and Chemistry

Murder Most Florid by Mark Spencer, London: Quadrille, 2019

As mentioned in the last post, herbaria, both real and virtual, are most frequently visited by taxonomists, who are usually studying particular plant taxa or preparing flora of areas ranging in size from city parks to entire countries.  These are the traditional uses of plant collections and are still crucial.  However, several things have changed.  Now the “visit” is often to digital portals rather than onsite, making it much easier for researchers to look at specimens from far-flung institutions, IF the material has been digitized, and particularly if it is available through aggregators such as iDigBio, GBIF or JSTOR Global Plants with their links to massive numbers of specimens.  Still, coverage is uneven, with some collections more fully digitized than others.  Also changed is the way taxonomic information, once generated, is distributed.  Many flora are now published virtually, with or without an accompanying paper format.  The 2012 International Code of Nomenclature for Algae, Fungi, and Plants made it acceptable to publish descriptions of new species digitally as long as they were responsibly published and properly archived.

Plant taxonomy is also changing because of its increasing links with genetics.  Most treatments of species and genera now include DNA sequencing data.  While this has been going on for decades, the last ten years or so have seen greater use of DNA data derived from samples taken from herbarium specimens, with NGS, next-generation sequencing (NSG) making this possible. NGS techniques utilize small pieces of degraded DNA found in dried plant material easier to sequence and to determine how such sequences fit together to provide meaningful results.  That this work has revolutionized taxonomy is hardly news.  Still, it is interesting to look at how the information has solved various puzzles, such as the origin of European potatoes or the origin of the pathogenic Phytophthora strain responsible for the Irish potato famine of the 1840s.  In a study of the genetics of grapes, researchers used over 200-year-old specimens from the herbarium at the Royal Botanical Garden in Madrid.  These plants were collected by Simón de Rojas Clemente y Rubio, considered one of the founders of the botanical study of grape vines, especially varieties used in wine-making.

DNA is not the only chemical being extracted from specimens to glean useful information about plants and also about their ecological relationships.  For example, researchers in Copenhagen tested specimens of four species of Salvia used for medicinal purposes for levels of terpenoids, known to have medicinal applications.  These plants were collected over the past 150 years.  While the terpenoid levels did decrease with the specimen’s age, the “chemical composition of four Salvia species are predominantly defined by species, and there was a substantially smaller effect of year of sampling.  Given these results, herbarium collections may well represent a considerably underused resource for chemical analyses.”  Also being investigated are secondary metabolites that plants produce to control herbivore damage.  In one study researchers were able to extract pyrrolizidine alkaloids from plants in the Apocynaceae family that includes milkweed.  The specimens were as much as 150 years old, and even in those treated with alcohol or mercuric chloride, alkaloids were detectable.

There has also been work on the presence of heavy metal pollutants in collections as a way of tracking contamination.  A study at Brown University in Providence, Rhode Island analyzed samples from specimens collected around the city from 1846 to 1916, compared with newly collected ones.  Levels of copper and zinc remained relatively consistent, but lead levels were much lower in plants growing in Providence today.  It was impossible to test accurately for another toxic heavy metal, mercury, because mercuric chloride was so often used to prevent insect damage to specimens.  While toxic metals in plants might make them seem less palatable as food sources, there is an emerging field of agromining:  growing plants that are hyper-accumulators of metals like lead and mercury to eventually reduce soil contamination.  Herbarium specimens can be used to discover how long areas have been contaminated and also to identify species that are particularly good at extracting metals.  There are even some who think that growing plants in nickel-rich soil could be a way to extract this metal for sale.

Such studies suggest that the possible uses of specimens are only limited by the ingenuity of researchers in coming up with them.  It is fun to see what they can ferret out.   The British botanist Mark Spencer recently published a book on his work as a forensic botanist.  It has a great title:  Murder Most Florid (2019).  He was at the herbarium at the Natural History Museum, London curating the British and European collections when he was first asked by the police to aid in a murder investigation.  Human remains have been found in a forested area and had apparently been there for several years.  Would he be able to determine the time more precisely by studying plants at the site?  I don’t want to spoil this story or the other great ones in the book, but I will say that Spencer explains why a herbarium is essential for the work he does, now that he has become much more involved in forensics.

Reference

Spencer, M. (2019). Murder Most Florid: Inside the Mind of a Forensic Botanist. London, UK: Quadrille.